In the related art, for example, in a series type hybrid vehicle including a traveling motor that drives driving wheels of a vehicle, a power generating motor that is coupled to an internal combustion engine of the vehicle, an inverter using pulse width modulation that controls each motor, and a boosting converter that boosts the direct current (DC) voltage of a DC power source and supplies the boosted DC voltage to each inverter, there is known a power source control apparatus for a rotating electrical machine that performs the processing of lowering the output voltage of the boosting converter in accordance with the magnet temperature of each motor to thereby lower the magnet temperature, with respect to each motor (for example, refer to Patent Document 1).